Effect of Rab23 on the proliferation and apoptosis in breast cancer.

Rab23, as a negative regulatory molecule of the Hedgehog (Hh) signaling pathway, may be a new target for treating carcinoma. In the present study, we aimed to determine whether Rab23 is expressed in breast cancer cells and whether Rab23 affects the viability and proliferation of breast cancer cells. We evaluated Rab23 expression in several breast cancer cell lines including MDA-MB-231, Bcap37 and MCF-7 by reverse transcription-PCR (RT-PCR), western blotting and immunofluorescence in vitro. We assessed cell growth and proliferation by 3-(4,5-dimethylthiazol‑2-y1)‑3,5-diphenyltetrazolium bromide (MTT), colony formation and bromodeoxyuridine (BrdU) incorporation assays. The distribution of the cell cycle and the rate of apoptosis were assessed using flow cytometry (FCM). In addition, we determined the mechanisms by which Rab23 regulates the Hh pathway by detecting the level of Gli molecules by RT-PCR. We found that Rab23 mRNA and protein levels were expressed in breast cancer cells, and the expression of Rab23 in MDA-MB-231 cells was higher than that in the MCF-7 cells. Rab23 protein was primarily expressed and localized in the cytoplasm surrounding the nucleus. The MTT assay showed that the absorbance value at A(490 nm) of the Rab23‑transfected group was reduced in comparison with the control group. The number of colonies formed in the breast cancer cells was significantly reduced and BrdU labeling was weakened in the group transfected with Rab23. The results of FCM showed that overexpression of Rab23 protein caused cell cycle arrest in the G1 phase and a decrease in the S phase population as well as induction of apoptosis. Furthermore, Rab23 decreased Gli1 and Gli2 mRNA levels when compared with the control group. Our results indicate that Rab23 is expressed in breast cancer cells, and ectopic expression of Rab23 inhibits the growth and proliferation as well as induces cell apoptosis in breast cancer cells. These effects may be due to the inhibition by Rab23 of Gli1 and Gli2 mRNA expression. These results suggest that Rab23 is a potential target for the treatment of breast cancer.